Piston ring

ABSTRACT

A spacer-expander ring for piston oil ring assemblies which can be economically and easily manufactured in continuous strip form, rolled and cut into split rings of desired size and heat treated to snap into a closed continuous ring with a diameter less than the diameter of the piston for which it is intended. The ring is circumferentially continuous, its ends will not overlap and it has individual spring fingers at its innermost periphery to engage the inner peripheries of thin split rail rings supported thereon.

United States Patent Prasse et al.

Oct, 2, 1973 PISTON RING Inventors: Herbert F. Prasse, Town and Country;Harold E. McCormick, Ballwin, both of Mo.

Assignee: Ramsey Corporation, St. Louis, Mo.

Filed: Mar. 23, 1971 Appl. No.: 127,177

Related US. Application Data Division of Ser. No. 802,351, Feb. 26,1969, Pat. No. 3,606,354.

11.8. CI 277/140, 277/141, 267/15 Int. Cl .7. F16] 9/20 Field of Search277/140, 200, 139,

References Cited UNITED STATES PATENTS I 12/1971 Prasse 277/140 PrimaryExaminer-Samuel B. Rorthberg Att0rneyHill, Sherman, Meroni, Gross &Simpson 2 Claims, 6 Drawing Figures PATENTED T 2l973 762.728

I N VEN TORS BY QQ @WTTORNEYS PISTON RING RELATED APPLICATION Thisapplication is a division of our copending application Ser. No. 802,351entitled Piston Ring, filed Feb. 26, 1969, now U.S. Pat. No. 3,606,354.

FIELD OF THE INVENTION This invention relates to the packing or pistonring art and more particularly to spacer-expander rings for oil controlpiston ring assemblies.

DESCRIPTION OF THE PRIOR ART Spacer-expander rings for oil controlpiston ring assemblies are usually of the circumferential expansion orgarter spring-type such as shown for example in the Marien United StatesLetters Patent Nos. 2,744,803 and 2,830,861. These rings can be madefrom strip stock but much of the stock must be cut-away and theremaining portion crimped, corrugated or otherwise longitudinallyforeshortened to provide a circumferentiallly expansible ring. This typeof ring must be contracted into the ring groove of the piston in orderthat.

it may exert a radial expanding force on the rail rings suportedthereby. Such contraction tends to overlap the split ends of the ringrequiring end abutment tabs and the like to stop the overlapping.Further, since the rings are circumferentially segmented they do nothave the strength of a continuous ring.

SUMMARY OF THE INVENTION The present invention now provides acircumferentially continuous spacer-expander ring made from a minimumamount of strip stock and having individual spring fingerscircumferentially spaced around its inner periphery and extendingaxially beyond the rail ring supporting surfaces thereof to engage theinner peripheries of the rail rings for exerting an expanding forcethereon. The ring is manufactured from continuous metal strip stock,rolled and cut into split rings of desired size and tempered to snapinto a closed continuous ring with the ends abutting and having adiameter less than the diameter of the piston for which it is intended.Since the ring is not circumferentially contracted in use there is notendency for its ends to overlap and special shaped end abutmentsheretofore required are not necessary. Thus the strip stock from whichthe rings are formed may be segmented into lengths for forming thedesired diameter rings without loss of material between segments.

The individual spring fingers at the inner periphery of.

the rings of this invention are inwardly of the circumferentiallycontinuous ring portions which support the rails and these rails do nothave to be decreased in radial depth such as is necessary when thefingers are outwardly from the inner periphery of the supporting ring.The fingers have angled tab ends to dish the rails into side sealingengagement with the ring groove. Firmer support "for the rail rings isprovided since they are engaged by the fingers at their inner.peripheries and rest on continuous ring areas near their outerperipheries.

The spacer-expander rings of this invention will not accept the railrings except on the proper supporting surfaces thereof since no openchannels are provided between the supporting surfaces.

The spacer-expander rings of this invention may take many differentshapes and forms all of which however include a circumferentiallycontinuous split ring with abutted together ends and individual springfingers circumferentially spaced around the inner periphery of the ringand extending axially beyond the rail ring supporting surfaces thereofso as to engage the inner peripheries of the rail rings.

It is then an object of this invention to provide spacer-expander ringsfor oil control piston ring assemblies which have a circumferentiallycontinuous ring portion and individual spring fingers spacedcircumferentially around the inner periphery of the rings for engagingthe inner peripheries of rail rings supported thereon.

Another object of this invention is to provide an abutment type splitspacer-expander ring which will not overlap in a ring groove and whichwill radially expand rail rings supported thereon without beingcircumferentially contracted.

Another object of this invention is to provide a spacer-expander oilcontrol ring for pistons which is manufactured from continuous metalstrip stock without longitudinally foreshortening the stock.

Another object of the invention is to provide a circumferentiallycontinuous spacer-expander ring with abutted together ends and rail ringexpanding fingers at the inner periphery of the ring.

Another object of the invention is to provide a spacer-expander ring forrail ring type oil control piston ring assemblies which has individualspring fingers around the inner periphery thereof acting on the innerperipheries of the rail rings causing them to dish into side sealingengagement with the sides of a piston ring groove as they are urgedradially outward.

Other and furtherobjects of this invention will become apparent to thoseskilled in this art from the following detailed description of theannexed sheet of drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a plan view of an oil controlring assembly in accordance with this invention with parts broken awayto illustrate underlying parts;

FIG. 2 is a fragmentary vertical cross-sectional view of a piston andcylinder illustrating the oil ring' groove in the piston equipped withthe ring assembly of FIG. I;

FIG. 3 is a fragmental isometric illustration of one form ofspacer-expander ring of this invention;

FIG. 4 isa front-end elevational view of the ring of FIG. 3;

FIG. 5 is a transverse cross-sectional view of the ring taken along theline V-V of FIG. 4;.and

FIG. 6 is a fragmentary plan view of a blank of metal strip stock fromwhich the ring of FIGS. 3 to 5 is formed.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate acomplete oil control ring assembly 10 including a spacer-expander ring11 of this invention supporting and expanding a pair of thin splitexpandable metal rail rings12 and I3. The top rail ring 12 has its ends12a slightly spaced apart so that a clear ance gap 14 is providedtherebetween. Likewise, the bottom ring 13 has its ends 13a spaced apartproviding a clearance gap 15 therebetween. The ends 11a of thespacer-expander ring 11 however are butted together and no gap existstherebetween so that the ring in its operating position is a continuouscircle.

The assembly as shown in FIG. 2 is carried in the oil ring groove G of apiston P which is mounted in an engine cylinder C. The groove G hasholes H in the bottom thereof communicating with the interior of thepiston for free flow of oil in the groove G.

As shown in FIG. 2 the rail rings 12 and 13 are supported in axiallyspaced relation on the spacerexpander ring 11 and have their innerperipheries engaged by the ring at an angle which dishes the rails intoside sealing engagement with the side walls of the ring groove and urgesthe rings radially outward into sealing engagement with the cylinder C.The assembly 10 is thus known as a rail ring type side sealing oilcontrol ring which allows free circulation of oil in the ring groovebetween the rails but seals the oil against leakage between the pistonand cylinder beyond the rail rings.

The spacer-expander 11, as best shown in FIG. 3, includescircumferentially continuous top and bottom ring portions 16 and 17connected in axially spaced parallel relation by circumferentiallyspaced axially upstanding integral legs 18 around the inner periphery ofthe ring with each leg 18 having a straight axially upstanding portionl8a with curved ends 18b extending radially outward to the innerperipheries 16a and 17a respectively of the ring portions 16 and 17.These ring portions 16 and 17 have outer peripheral edges 16b and 1712respectively which are radially outward from the inner peripheries aconsiderable distance. Flat top and bottom faces of appreciable radialdepth are thus provided by the rings 16 and 17.

The legs 18 alternate with spring fingers 19 and 20 respectivelydepending from the top ring 16 and the bottom ring 17.

Each finger 19, as shown in FIGS. 3 to 5, has a main portion 19adepending from a rounded top end 19b which extends radially inward fromthe inner edge 16a of the top ring 16 to the same extent as the roundedends 18b of the legs 18 and then the portion 19a slopes axially downwardand radially outward as shown in FIG. 5 into close spaced relation withthe inner edge 17a of the bottom ring 17. The fingers 19 have end tabs19c projecting beneath the ring 17 and bent backwardly to provide anabutment front face 19d at an angle, preferably 7 to 12 from thevertical.

The fingers 20 are shaped and formed in the same manner as the fingers19 with upwardly and outwardly extending main portions 20a dependingfrom rounded ends 20b which extend radially inward from the ring 17 tothe same depth as the fingers 18 and with the portions 20a extendingoutwardly close to the rear edge 16a of the top ring 16. An abutment tab20c on each finger 20 then extends beyond the top ring 16 and is angledbackwardly at the same angle as the'tab 190 to provide the abutment face20d.

Struts 21 and 22 depend alternately from the top and bottom rings 16 and17 at the outer peripheral edges of these rings with the struts 21depending from the top ring 16 being bottomed on the bottom ring 17 andwith the struts 22 depending from the bottom ring 17 being bottomed onthe top ring 16. The struts 21 and 22 are equally spaced around theperiphery .of the ring and prevent the rail rings from entering thechannel between the rings 16 and l7.

As shown in FIG. 2, the rail rings 12 and 13 have their inner edgesengaged by theangled abutment faces 20d and 19d respectively of thespring fingers 20 and 19 and these fingers are bent back from their freestate condition of FIG. 5 so as to exert radially outward and axiallyoutward expanding forces on the rings 11 and 12 urging their outerperipheries into good sealing condition with the cylinder C.

The rail rings 12 and 13 are supported on the ring portions 16 and 17 ofthe spacer-expander 11 near the outer peripheral ends of these rings andthe rail rings are free to rock on the surfaces provided by these rings16 and 17.

It should be understood that in the free state condition of the ring 11the ends 11a thereof are abutted. The ring is easily slipped over thepiston to snap into the groove G and when its ends are abutted togetherin the groove the inner periphery of the ring is of larger diameter thanthe ring groove so that the back wall of the ring groove is spaced fromthe inner periphery of the assembly as shown in FIG. 2. The ring 11 isnot circumferentially compressed in the ring groove and therefore itsends 11a have no tendency to overlap. No special end abutment tabs needbe provided as in the case of garter spring type rings.

The spring fingers 19 and 20 act independently on the rail rings 12 and13 to provide their spring force action from bases which are solidcontinuous rings 16 and 17. In the operative position, the abutmentfaces 19d and 20d of the spring fingers are at the inner periphery ofthe spacer-expander 11 and the rail rings 12 and 13 can have the sameradial depths as when used in garter spring type assemblies.

As shown in FIG. 6, the ring 11 is made from a blank 23 that is punchedout from a continuous metal strip. The blank 23 has parallel side edges24 and is transversely punched to provide adjacent pairs of cut-outportions 25 separated by a strip 26. Alternate strips 26 have oppositeends 27 and 28 severed from the blank to provide free ends for thestrips.

The pairs of cut-outs 25 are separated from each other by strips 29wider than the strips 26. Continuous margin portions 30 and 31 extendinwardly from the edges 23 and 24 to the ends of the punched outsections 25. Each marginal portion 30 and 31 is lanced at intervals,preferably alternately overlying the pairs of punched out portions 25.Thus, the marginal portion 30 has a longitudinal cut 32 parallel withthe edge 23 terminating in a transverse cut 33 extending to the end edge23. The cut 32 is about the same length as the distance between thestrip portions 29.

The marginal portion 31 is similarly cut with a longitudinal cut 34terminating in a transverse cut 35.

The blank 23 is bent into a u-shape with the marginal portions 30 and 31forming the top and bottom rings 16 and 17 of the finished ring 11, withthe portions 29 forming the legs 18 of the ring, with the portions 26forming the spring fingers l9 and 20 and with the cutout portionsprovided by the cuts 32-35 forming the struts 21 and 22. The ring 1 1can be formed in a continuous strip form, cut into segments for formingthe rings of desired diameter, coiled into ring shape with the endsabutting, and heat treated so that the coil rings will have their endsabutted together in the free state. The material forming the ring can bea steel such as SAE I075 and a coining operation can be used toaccurately shape the abutment faces 19d and 20d of the tingers.

For 1075 material the heat treatment may consist of heating the finishedrings to 1500 F and quenching in oil. This is followed by a temperingoperation in which the rings may be heated to 600 F. for one hour tosecure the desired spring properties and a hardness in the range of45-55 Rockwell C.

It will be understood, however, that other materials than 1075 steel canbe used in which the heat treatment may be altered to acquire thedesired spring properties.

From the above description it will be understood that thespacer-expanders of this invention do not contract circumferentially inoperation, have two continuous circumferential portions, and haveindividual spring fingers projecting axially above andbelow theseportions radially inwardly therefrom to expand and dish rail ringsresting on the portion or portions.

Although various minor modifications might be suggested by those versedin the art, it should be understood that we wish to embody within thescope of the patent warranted hereon all such modifications asreasonably and properly come within the scope of our contribution to theart.

We claim 'as our invention:

1. A spacer-expander ring for oil control piston ring assemblies whichcomprises a split metal ring having abutted-together ends in operationand axially spaced top and bottom radially extending continuouscircumlegs each having one end extending radially inward from the innerperiphery of one wall providing an additional surface adapted to supportthe rail rings, each of the spring fingers extending axially andradially outward, and having a free end projecting above the other wall,said spring fingers being alternately arranged to provide free endsbeyond both walls on opposite sides of the legs for engaging the innerperipheries of rail rings supported on the walls, said free ends beingangled radially inward and struts formed from portions of the outerperiphery of the continuous circumferential wall bent axially to spanthe distance between the walls, preventing the walls from moving axiallytowards one another, and said fingers and said legs beingcircumferentially spaced from one another to provide drainage radiallythrough said ring.

2. The ring of claim 1 wherein one strut depends from one wall and theadjacent strut depends from the opposite wall and the free ends of thestruts engage the walls opposite those from which they depend.

1. A spacer-expander ring for oil control piston ring assemblies whichcomprises a split metal ring having abutted-together ends in operationand axially spaced top and bottom radially extending continuouscircumferential walls between said ends connected by circumferentiallyspaced legs around the inner periphery of the ring with ends extendingrAdially inward from said continuous circumferential walls andcooperating therewith to provide top and bottom surfaces adapted tosupport rail rings mounted thereon, and circumferentially spacedupstanding spring fingers between said legs each having one endextending radially inward from the inner periphery of one wall providingan additional surface adapted to support the rail rings, each of thespring fingers extending axially and radially outward, and having a freeend projecting above the other wall, said spring fingers beingalternately arranged to provide free ends beyond both walls on oppositesides of the legs for engaging the inner peripheries of rail ringssupported on the walls, said free ends being angled radially inward andstruts formed from portions of the outer periphery of the continuouscircumferential wall bent axially to span the distance between thewalls, preventing the walls from moving axially towards one another, andsaid fingers and said legs being circumferentially spaced from oneanother to provide drainage radially through said ring.
 2. The ring ofclaim 1 wherein one strut depends from one wall and the adjacent strutdepends from the opposite wall and the free ends of the struts engagethe walls opposite those from which they depend.